Field of electric actuating systems aboard aircrafts

ABSTRACT

An actuating system for an aircraft having an electromechanical actuator ( 25 ) comprising a non-volatile memory ( 60 ) wherein stored data ( 61 ) including configuration data ( 62 ) specific to the electromechanical actuator is stored. The system also includes a control unit ( 22 ) using the configuration data to implement a servo-control loop, the output signal of which is a digital signal controlling the electric motor of the electromechanical actuator and at least one digital transmission channel ( 50 ) connecting the control unit and the electromechanical actuator.

BACKGROUND OF THE INVENTION

Many systems are provided aboard aircrafts, which consist of mobileparts which have to move.

Wing elements (for example an aileron, a flap, an air brake), elementsof the landing gear (for example a landing gear strut movable between anextended position and a retracted position, or a plunger of a brake of awheel which slides relative to brake friction members), elements makingit possible to implement variable geometry turbines, elements of a pumpor a fuel metering mechanism, elements of the thrust reversers, elementsof a propeller pitch driving mechanism (for example on an helicopter ora turboprop engine), etc. belong to such mobile parts.

On modern aircrafts, more and more electromechanical actuators are usedto implement such mobile parts. As a matter of fact, the advantages ofusing electromechanical actuators are numerous: simple electricdistribution and driving, flexibility, simplified maintenanceoperations, etc.

An electromechanical actuator conventionally comprises a mobileactuating member which moves the mobile part, an electric motor intendedto drive the mobile actuating member and thus the mobile part, and oneor more sensor(s) for the various parameters of the electromechanicalactuator.

An airborne electric actuating system wherein such an electromechanicalactuator is integrated conventionally implements the followingfunctions: definition of a set-point according to the function to befulfilled (for instance a speed, position or force set-point),measurement of an electromechanical actuator servo-control parameter(for instance speed, position, force), execution of a servo-control loopenabling the electromechanical actuator to reach the set-point,generation of electric current supplying the electric motor, andtransformation, by the electric motor, of the electric energy into amechanical energy which drives the actuating member and thus the mobilepart.

The functions of executing the servo-control loop and generatingelectric supply current are generally implemented in one or morecentralized computer(s): this is called a centralized architecture.

In reference with FIG. 1, a known aircraft brake 1 comprises fourelectromechanical actuators 2 which are grouped in two distinct arraysof two electromechanical actuators 2. The electromechanical actuators 2of a distinct array are connected to the same centralized computer 3positioned in the aircraft bay. The electric motor of eachelectromechanical actuator 2 receives electric current supplying thecentralized computer 3 which the electromechanical actuator 2 isconnected to, and each electromechanical actuator 2 transmitsmeasurements of a servo-control parameter to the centralized computer 3(for instance, measurements of the angular position of the rotor of theelectric motor).

Two different configurations of such a centralized architecture thusexist, which can be differentiated by the place where the set-point isdefined.

In a first configuration, shown in FIG. 2, means for generating theset-point 5 of each centralized computer 3 define the set-point andtransmit it to processing means 6 of the centralized computer 3. Theprocessing means 6 of the centralized computer 3 then execute aservo-control loop. The electromechanical actuator 2 transmits themeasurements of the servo-control parameter obtained from a sensor 7 tothe centralized computer 3, with said measurements being theservo-control loop feedback signal. The servo-control loop output signalis transmitted to a power module 8 drive, then to a power module 9 ofthe centralized computer 3 which generates the electric currentsupplying the electric motor 10 of the electromechanical actuator 2. Theelectric motor 10 then drives the actuating member 11. Implementing theservo-control loop requires parameters stored in a memory 12 of thecentralized computer 3. The power module 9 of the centralized computer 3is supplied by a supply unit 13 outside the centralized computer 3.

In a second configuration, shown in FIG. 3, the centralized computer 3is dedicated to the servo-control of the electromechanical actuator 2and to the generation of the electric supply current, and it no longerdefines the set-point which is supplied by another equipment 14 via adigital bus 15, for instance (the transmission is symbolized byreference T1 in FIG. 3).

It should be noted that both such architecture configurations have somedrawbacks. The centralized computer 3 thus has to be dimensionedaccording to the technology of the electromechanical actuator 2 used andthe parameters of the servo-control loop have to be adapted to thedimensions of the electromechanical actuator 2 used. The centralizedcomputer 3 and the electromechanical actuator 2 thus tend to be mated,which makes a modification in the electromechanical actuator 2 and amodification in the parameterization of the servo-control loop resultingfrom the change in technology very complex and very expensive.

Besides, the electric wires between the centralized computer 3 and theelectromechanical actuator 2 carry high varying current which requirescomplex precautions to be implemented to control the electromagneticemissions.

OBJECT OF THE INVENTION

The invention aims at reducing the complexity and cost of an electricactuating system.

SUMMARY OF THE INVENTION

To reach this goal, an actuating system for an aircraft is proposed,which comprises:

an electromechanical actuator which comprises an electric motor, a powermodule intended to generate a current supplied to the electric motor,measuring means adapted for measuring a control magnitude of theelectromechanical actuator and for generating a digital measurementsignal representative of the servo-control magnitude, and a non-volatilememory wherein stored data including configuration data specific to theelectromechanical actuator is stored;

a control unit intended to execute a servo-control algorithm byacquiring and using configuration data to adapt the servo-controlalgorithm to the electromechanical actuator, with the servo-controlalgorithm implementing a servo-control loop, the feedback signal ofwhich is the digital measurement signal and the output signal of whichis a digital signal controlling the electric motor of theelectromechanical actuator intended to the power module;

at least one data channel connecting the control unit and theelectromechanical actuator and enabling the routing of the digitalmeasurement signal, the data stored and the digital control signal.

Using the non-volatile memory positioned in the electromechanicalactuator and comprising configuration data specific to theelectromechanical actuator makes it possible to mutualize the controlunit by using same in various electric actuating systems integratingdifferent electromechanical actuators. The cost of such electricactuating systems, and the complexity of said systems development, isthus reduced since it is no longer necessary to totally develop acontrol unit for each one of said systems. Besides, designing thecontrol unit no longer requires to know the configuration data specificto the electromechanical actuator used (and even no longer requires toknow the technology specific to the electromechanical actuator used).The interactions required between the development activities of thecontrol unit and the electromechanical actuator are thus reduced, andthe complexity of such development, and therefore the cost of theelectric actuating systems is reduced again.

Other characteristics and advantages of the invention will becomeapparent upon reading the following description of particularnon-restrictive embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is made to the appended drawings, wherein:

FIG. 1 shows a braking system architecture of the prior art;

FIG. 2 shows a first actuating system of the prior art;

FIG. 3 shows a second actuating system of the prior art;

FIG. 4 shows a braking system architecture of a system according to afirst embodiment;

FIG. 5 shows a braking system architecture of a system according to asecond embodiment;

FIG. 6 shows an actuating system according to a first embodiment of theinvention;

FIG. 7 shows an actuating system according to a second embodiment of theinvention;

FIG. 8 shows an actuating system according to a third embodiment of theinvention;

FIG. 9 shows an actuating system according to a fourth embodiment of theinvention;

DETAILED DESCRIPTION OF THE INVENTION

The invention is implemented here on an aircraft which comprises aplurality of main landing gears each carrying a plurality of so-called“braked” wheels, i.e. a plurality of wheels equipped with a brakeintended to brake the aircraft. The present description relates to asingle braked wheel, but the invention of course applies in the same wayto all or part of the braked wheels of the aircraft or to any otherdevice of an aircraft or the motorization thereof implementing anelectromechanical actuator.

In reference to FIG. 4, a braking system architecture according to afirst embodiment thus comprises a brake 20 intended to brake a wheel ofthe aircraft, a first supply unit 21 a, a second supply unit 21 b, afirst control unit 22 a, a second control unit 22 b and a network switch23.

The brake 20 comprises an actuator-holder whereon four brakingelectromechanical actuators 25 a, 25 b, 25 c, 25 d and friction members,i.e. a stack of carbon disks are mounted.

The four electromechanical actuators 25 are used to apply a brakingforce onto the stack of carbon disks and thus exert a braking torqueonto the wheel which slows down the rotation of the wheel and thus slowsthe aircraft down when the latter touches the ground.

Each electromechanical actuator 25 comprises a body attached to theactuator-holder, a plunger and a locking member adapted for locking theplunger in position. An electric motor, a power module and a digitalcommunication module 26 are integrated into the body of eachelectromechanical actuator 25.

The plunger is actuated by the electric motor to slide and apply thebraking force onto the stack of carbon disks.

The power module makes it possible to generate an alternating supplycurrent which circulates in three phases of the electric motor when theplunger has to be actuated to brake the wheel. For this purpose, thepower module comprises an inverter comprising a plurality of switcheswhich are so controlled as to transform a direct supply voltage Vc intoan alternating voltage at which the current supplying the electric motoris generated.

The supply voltages Vc received by the power modules of the fourelectromechanical actuators 25 of the brake are delivered by the firstsupply unit 21 a and the second supply unit 21 b.

The four electromechanical actuators 25 are grouped into a first arrayand a second distinct array, with the first array comprising theelectromechanical actuators 25 a and 25 b and with the second arraycomprising the electromechanical actuators 25 c and 25 d.

The first supply unit 21 a supplies the supply voltage Vc to the powermodules of the electromechanical actuators 25 a and 25 b of the firstarray, whereas the second supply unit 21 b supplies the supply voltageto the power modules of the electromechanical actuators 25 c and 25 d ofthe second array.

To receive the supply voltage Vc, each electromechanical actuator 25 isconnected to the first supply unit 21 a or to the second supply unit 21b by two power supply wires 28.

The first supply unit 21 a and the second supply unit 21 b are placed inthe bay, in the aircraft fuselage, above the landing gear.

Besides, the power module of each electromechanical actuator 25 uses adigital control signal Sc to control the inverter switches.

The digital control signals Sc of the four electromechanical actuators25 are generated by the first control unit 22 a and by the secondcontrol unit 22 b.

This time, each control unit 22 generates digital control signals Sc tobe sent to the four electromechanical actuators 25. The first controlunit 22 a and the second control unit 22 b are thus redundant, so thatthe loss of one of the two control units 22 does not affect the brakingperformances.

The first control unit 22 a and the second control unit 22 b are placedin the bay, in the aircraft fuselage, above the landing gear.

The distribution of the digital control signals Sc to the power modulesof the four electromechanical actuators 25 is executed via the digitalcommunication modules 26 of the four electromechanical actuators 25,with each digital communication module 26 of one electromechanicalactuator 25 transmitting to the power module and thus to the inverter ofthe power module of said electromechanical actuator 25 the digitalcontrol signals Sc which are to be sent thereto.

The digital communication modules 26 of the four electromechanicalactuators 25 are interconnected to form a digital network 30 (digitalnetwork means, here, an assembly of interconnected communicating devicesexchanging data as digital signals). The digital network 30 is herering-shaped.

The network switch 23, which is connected to the first control unit 22 aand to the second control unit 22 b, is integrated in the digitalnetwork 30.

The network switch 23 is thus connected to the digital communicationmodules 26 of two electromechanical actuators 25 of the brake 25 a and25 c, so as to build, too, one of the entities forming the closed loopof the ring-shaped digital network 30, with the digital communicationmodules 26 of the four electromechanical actuators 25 building the otherentities. Each entity (the digital communication module 26 or thenetwork switch 23) of the digital network 30 is connected by fourcommunication electric wires 32 to two distinct entities.

The network switch 23 manages the operation of the digital network 30 bydistributing the digital control signals Sc from the first control unit22 a and the second control unit 22 b to the digital communicationmodules 26 via the digital network 30.

The network switch 23 is here positioned with the first control unit 22a and with the second control unit 22 b in the same box (which is thusplaced in the bay, in the aircraft fuselage, above the landing gear).

The transmission to the digital communication modules 26 and thus to thepower modules of the digital control signals Sc from the control units22, and the supply of the power modules with the supply voltage Vc fromthe supply units 21 thus require sixteen electric wires which run fromthe top of the landing gear to the brake 20, instead of the twenty-eightelectric wires of the architecture of FIG. 1.

It should be noted that the digital network 30 which has just beendisclosed is not used for transmitting the digital control signals Sc tothe power modules of the electromechanical actuators 25 only.

The uplink digital signals Sm are also transmitted from the brake 20 tothe control units 22 via the digital network 30 and thus via the networkswitch 23.

The uplink digital signals Sm firstly comprise digital measurementsignals emitted by the digital communication modules 26 and emitted bysensors integrated in the electromechanical actuators 25. Themeasurement digital signals are here signals for measuring the angularposition of the rotors of the electric motors, signals for measuring thecurrents supplying the electric motors, and signals for measuring theforce produced by the electromechanical actuators 25 actuating member.

The angular position measuring signals are emitted, for eachelectromechanical actuator 25, from an angular position sensorintegrated in said electromechanical actuator 25.

The angular position measuring signals are emitted, for eachelectromechanical actuator 25, from a current sensor integrated in saidelectromechanical actuator 25.

The force measuring signals are emitted, for each electromechanicalactuator 25, from a force sensor integrated in said electromechanicalactuator 25.

The angular position, current and force measuring signals aredigitalized by the communication modules 26, emitted on the digitalnetwork 30 and used by the control units 22 for generating the digitalcontrol signals Sc and controlling the electric motors of the fourelectromechanical actuators 25.

The uplink digital signals Sm then comprise electromechanical actuators25 monitoring signals emitted by the digital communication modules 26.

The electromechanical actuators 25 monitoring signals are intended tosupply a state of the electromechanical actuators 25 from which thecontrol units 22 may make the decision to order a maintenance operation,or to totally or partially deactivate one or more electromechanicalactuator(s) 25.

Eventually, the uplink digital signals Sm comprise measurement signalstransmitted to the electromechanical actuators by an external sensorpositioned on the wheel (not shown in FIG. 4). The external sensor ishere a brake torque sensor positioned on the brake 20. The externalsensor is integrated in the digital network 30 (it also forms one entityof the ring digital network). It comprises a digital interface which,like the digital communication modules 26 mentioned above, enables theexternal sensor to transmit the torque measurements to the control units22 via the digital network 30.

Besides, in addition to the digital control signals Sc, additionaldownlink digital signals Sd are transmitted from the control units 22 tothe brake 20 via the digital network 30.

The additional downlink digital signals Sd firstly compriseelectromechanical actuators 25 functional test signals and sanctionsignals.

The functional test signals trigger the execution of functional tests bythe electromechanical actuators 25 with a view to making a diagnosisrelating to the operation of the electromechanical actuators 25 (and,optionally, relating to the efficiency of communications from and to theelectromechanical actuators 25).

The sanction signals enable the control units 22 to “penalize” anelectromechanical actuator 25 by totally or partially deactivating same,or by excluding the digital communication module 26 thereof from thedigital network 30.

The additional downlink digital signals Sd also comprise signals forcontrolling another equipment mounted on the wheel, i.e. here a brakefan 20 (not shown in FIG. 4). The brake fan 20 is integrated in thedigital network 30 (it also forms one entity of the ring digitalnetwork). It comprises a digital interface which, like the digitalcommunication modules 26 mentioned above, enables the brake fan 20 toreceive the control signals from the control units 22 via the digitalnetwork 30.

In the braking system architecture according to a second embodiment,shown in FIG. 5, the digital network, this time, is a star digitalnetwork 40.

The network switch 23 forms a node of the digital star network 40 whichall the electromechanical actuators 25 of the brake 20 are connected to.

It should be noted that the braking system architecture according to thesecond embodiment comprises, in addition to the four electromechanicalactuators 25, the power supply units 21, the two control units 22 andthe network switch 23, a connexion box 41 mounted on the brakeactuator-holders 20.

The four electromechanical actuators 25, the two power supply units 21,the two control units 22 and the network switch 23 are connected to theconnexion box 41.

The connexion box 41 receives the continuous supply voltage and thedownlink digital signals mentioned above, and distributes same to theelectromechanical actuators 25 and to the brake torque sensor and to thebrake fan. The connexion box 41 also receives the uplink digital signalsmentioned above, and distributes same to the network switch 23 whichtransmits same to both control units 22.

Advantageously, whatever the embodiment of the brake systemarchitecture, the locking member of each electromechanical actuator 25is integrated too in the digital network 30 or 40. The locking member isthen locally supplied from the supply voltage received by theelectromechanical actuator 25 and issued by one of the supply units 21.The locking member receives control orders via the digital network 30,40 and emits a status on the digital network 30, 40.

The way each control unit 22 controls one of the four electromechanicalactuators 25, and thus generates the digital control signals Sc to besent to such electromechanical actuator 25 will now be described ingreater details.

Referring to FIG. 6, it is considered that one of the two control units22 and one of the four electromechanical actuators 25 form an actuatingsystem according to a first embodiment of the invention which, inaddition to the control unit 22 and the electromechanical actuator 25,comprises a digital transmission channel 50 which connects the controlunit 22 and the electromechanical actuator 25. The following alsoapplies to both control units 22 and to the four electromechanicalactuators 25 described above.

In the braking system architectures of FIGS. 4 and 5, the digitaltransmission channel 50 consists of the electric wires connecting thecontrol unit 22 with the network switch 23, through the network switch23, through the connexion box 41 as regards FIG. 5, and through thevarious elements of the digital network (electric wires, communicationmodules 26 of other electromechanical actuators 25) which separate thedigital communication module 26 of the electromechanical actuator 25involved from the network switch 23.

The control unit 22 comprises set-point generating means 51, processingmeans 52, and a digital communication interface 53.

As seen above, the electromechanical actuator 25 comprises acommunication module 26, a power module 54, an electric motor 55, aplunger 56 and measuring means 59 comprising sensors (for example acurrent sensor, an angular or linear position sensor, a force or torquesensor). The power module 54 comprises an inverter control 57 and aninverter 58.

Additionally, the electromechanical actuator 25 comprises a non-volatilememory 60 wherein stored data 61 including configuration data 62specific to the electromechanical actuator is stored.

The configuration data 62 comprises servo-control parameters 63 specificto the electromechanical actuator 25, the function of which is explainedhereunder.

The non-volatile memory 60, programmed during the manufacturing of theelectromechanical actuator 25, is compatible with the environmentalconditions (temperature, vibrations, shocks, electromagneticperturbations, etc.) which the electromechanical actuator 25, which ismounted on a brake actuator-holder, is exposed to. The non-volatilememory 60 is advantageously integrated in a semi-conductor component ofthe digital communication module 26.

The angular position measured by the angular position sensor of theelectromechanical actuator 25 and the current measured by the currentsensor of the electromechanical actuator 25 are servo-control magnitudesof the electromechanical actuator 25.

The measuring means 59 convert the measured servo-control magnitudesinto digital measurement signals representative of the servo-controlmagnitudes.

To control the electromechanical actuator 25, the processing means 52 ofthe control unit 22 execute a servo-control algorithm 67, the nativecode 65 of which is stored in a memory 66 of the processing means 52.

The servo-control algorithm 67 implements three interleavedservo-control loops intended to control the power module 54 of theelectromechanical actuator 25 via the digital channel 50: a currentservo-control loop, a speed servo-control loop and a positionservo-control loop.

The set-point of each servo-control loop is a set-point generated by theset-point generating means 51 of the control unit 22 or another controlunit of the aircraft.

The feedback signal of the current servo-control loop is the digitalmeasurement signal representative of the current, and the feedbacksignal of the speed and position servo-control loops are the digitalmeasurement signals representative of the angular position. The feedbacksignals are transmitted by the communication module of theelectromechanical actuator 25 to the control unit 22 via the digitaltransmission channel 50 (transmission T2 in FIG. 6).

The output signal of the servo-control algorithm is an electric motorcontrol digital signal 55 to be sent to the power module 54(transmission T3 in FIG. 6).

The digital control signals are transmitted to the power module 54 ofthe electromechanical actuator 25 via the digital interface 53 of thecontrol unit 22, the digital transmission channel 50 and the digitalcommunication module 26 of the electromechanical actuator 25(transmission T3 in FIG. 6). The inverter control 57 of the power module54 then controls the inverter 58 which generates a current supplied tothe electric motor 55 to drive the plunger 56 of the electromechanicalactuator 25 according to the set-point.

Implementing the servo-control loops uses the servo-control parameters63 specific to the electromechanical actuator 25, which comprise, here,a proportional coefficient, an integral coefficient and a derivedcoefficient, and a position limitation, a speed limitation and a powerlimitation of the electromechanical actuator 25.

Prior to using the electromechanical actuator 25, for example uponstarting the control unit 22 and the electromechanical actuator 25, theprocessing means 52 of the control unit 22 thus acquire theservo-control parameters 63 stored in the non-volatile memory 60 of theelectromechanical actuator 25 and integrate same into the servo-controlloops (transmission T4 in FIG. 6). The processing means 52 then have alldata required for executing the servo-control algorithm 67 and theservo-control loops.

Any modification in the design of the electromechanical actuator 25requiring a modification in the servo-control parameters 63 specific tothe electromechanical actuator 25 can thus be implemented by storing thenew servo-control parameters 63 in the non-volatile memory 60 of theelectromechanical actuator 25 only, and thus without modifying thecontrol unit 22. The costs entailed in the modification in the design ofthe electromechanical actuator 25 are thus reduced.

Referring to FIG. 7, the actuating system according to a secondembodiment of the invention again comprises the control unit 22, theelectromechanical actuator 25 and the digital transmission channel 50.

The non-volatile memory 60 of the electromechanical actuator 25 of thesystem according to the second embodiment of the invention is also usedfor parameterizing other algorithms.

The configuration data 62 among the stored data 61 stored in thenon-volatile memory 60 comprises, in addition to the servo-controlparameters 63 of the servo-control algorithm 67, parameters 70 of afailure detection algorithm 71 and/or a trend following algorithm 72and/or a cycle counting algorithm 73.

The failure detection algorithm 71, the trend following algorithm 72 andthe cycle counting algorithm 73 are stored in the memory 66 of theprocessing means 52 of the control unit 22. When one of these algorithms71, 72, 73 has to be executed, the control unit 22 acquires thecorresponding parameters 70 (transmission T5 in FIG. 7).

Referring to FIG. 8, the actuating system according to a thirdembodiment of the invention again comprises the control unit 22, theelectromechanical actuator 25 and the digital transmission channel 50.

The non-volatile memory 60 of the electromechanical actuator 25 of theactuating system according to the third embodiment of the invention isalso used for storing an identifier 80 of a servo-control algorithm tobe used for the electromechanical actuator 25.

The configuration data 62 among the stored data 61 stored in thenon-volatile memory 60 comprises an identifier 80 which enables theprocessing means 52 of the control unit 22 to select the servo-controlalgorithm to be used among a list of servo-control algorithms stored inthe memory 66 of the processing means 52.

The list of servo-control algorithms comprises a servo-control algorithm81 for an electromechanical actuator with an alternating current motor,a servo-control algorithm 82 for an electromechanical actuator with adirect current motor, a servo-control algorithm 83 for anelectromechanical actuator with a torque motor, a servo-controlalgorithm 84 for an electromechanical actuator with a step motor.

The electric motor 55 of the electromechanical actuator 25 is here analternating current motor. Prior to using the electromechanical actuator25, for example upon starting the control unit 22 and theelectromechanical actuator 25, the processing means 52 of the controlunit thus acquire the identifier 80 stored in the non-volatile memory 60of the electromechanical actuator 25 (transmissions T6 and T6″ in FIG.8). The processing means 52 select and then execute the servo-controlalgorithm 81 for an electromechanical actuator with an alternatingcurrent motor.

Changing the technology of the electric motor 55 of theelectromechanical actuator 25 which requires using a differentservo-control algorithm previously stored in the memory 66 of theprocessing means 52 can thus be implemented by storing the newidentifier in the non-volatile memory 60 of the electromechanicalactuator 25 only, without modifying the control unit 22.

Referring to FIG. 9, the actuating system according to a fourthembodiment of the invention again comprises the control unit 22, anelectromechanical actuator 25 and a digital transmission channel 50.

The non-volatile memory 60 of the electromechanical actuator 25 of thesystem according to the fourth embodiment of the invention is also usedfor storing a native code 90 of an already parameterized servo-controlalgorithm of the electromechanical actuator 25.

Prior to using the electromechanical actuator 25, for example uponstarting the control unit 22 and the electromechanical actuator 25, theprocessing means 52 of the control unit 22 thus acquire the native code90 of the servo-control algorithm in the non-volatile memory(transmissions T7 in FIG. 9).

Designing the control unit 22 thus does not require a previousdefinition of the servo-control algorithm.

It should be noted here that the native code of any type of algorithmcan be stored in the non-volatile memory 60 and not only the native codeof a servo-control algorithm (for instance, the native code of a failuredetection algorithm and/or a trend following algorithm and/or a cyclecounting algorithm).

Advantageously, and whatever the embodiment of an actuating systemdisclosed above, the non-volatile memory of the electromechanicalactuator 25 can be used to store configuration data comprisingelectromechanical actuator 25 calibration data. The calibration data canbe used by the control unit 22 to correct one or more set-point(s) ofthe servo-control loops or the digital measurement signals. Thecalibration data is, for example, data enabling a gradient correction,an offset correction or a correction according to the parametersmeasured by the sensors of the electromechanical actuator.

Storing the calibration data in the non-volatile memory 60 of theelectromechanical actuator 25 makes it possible to simplify thedevelopment of the electromechanical actuator 25 during the designingand the manufacturing thereof, and thus to reduce the design andproduction costs of the electromechanical actuator 25. Besides, thesystem performances are enhanced when calibrating the electromechanicalactuator 25 using the calibration data.

Whatever the embodiment of the actuating system described above, thenon-volatile memory 60 may advantageously contain data supplied by thecontrol unit 22. The non-volatile memory 60 is then read-accessibleand/or write-accessible by the control unit 22. The stored data isrouted between the electromechanical actuator 25 and the control unit 22on the transmission channel 50, whatever the routing direction.

The data supplied by the control unit 22 here comprises information onthe utilization of the electromechanical actuator 25, which is producedfrom other data stored in the non-volatile memory 60 of theelectromechanical actuator 25, or which is obtained when the controlunit 22 executes any algorithm.

Storing the utilisation information relative to the electromechanicalactuator 25 in the non-volatile memory 60 thereof facilitates the futuremaintenance operations. A maintenance operator will have access to theinformation on the utilisation of the electromechanical actuator 25without it being necessary to configure the control unit 22 or theelectromechanical actuator 25 according to a specific maintenanceconfiguration. Additionally, the future repair operations arefacilitated. A repair operator will have access to the information onthe utilisation of the electromechanical actuator 25 without it beingnecessary to transfer data from the control unit 22.

Whatever the embodiment of the actuating system described above, thenon-volatile memory 60 may advantageously contain other information usedby the servo-control algorithm, for monitoring, maintenance, productionand delivery of the electromechanical actuator 25. Among suchinformation, the reference or the serial number of the electromechanicalactuator 25 can be cited.

Such information can specifically be used during the initialisationphase of the electromechanical actuator 25.

Whatever the embodiment of the actuating system described above, thedata stored 61 in the non-volatile memory 60 is advantageously protectedby a checking tool of the cyclic redundancy check type which ensures theintegrity of the stored data 61 and the detection of corruption of suchstored data.

Whatever the embodiment of the actuating system disclosed above, thetransmission channel 50 advantageously consists of a fast channel and aslow channel.

The digital data which requires a fast transmission (like a real-timetransmission) is routed on the fast channel. This more particularlyrelates to the digital control signals and the digital measurementsignals used in the servo-control loops.

The digital data which does not require a fast transmission is routed onthe slow channel. This more particularly relates to the stored data 61of the non-volatile memory 60 upon writing or reading such stored data61.

The stored data 61 may further be read-accessible and/orwrite-accessible by a wireless interrogation device using RIFD-typetechnology. Such wireless access is particularly interesting whencarrying out maintenance operations on the electromechanical actuator25.

The communication module and/or the power module are advantageouslyintegrated in the same ASIC which may be developed for several types ofelectromechanical actuators, which reduces the so-called «not recurrent»development costs of such electromechanical actuators.

Of course, the invention is not limited to the specific embodimentsdescribed above, but on the contrary, encompasses any alternativesolution within the scope of the invention as defined in the claims.

Although the external sensor is mentioned to be a braking torque sensorpositioned on the brake, providing one or more different externalsensor(s) can be considered, for instance a disk stack temperaturesensor (typically a thermocouple), or a wheel tyre pressure sensor, orstill a tachometer.

Although the actuating system of the invention has been described withinan architecture of the braking system, the actuating system of theinvention can be integrated in the architecture of another type ofsystem: a propulsion system, a flight controls system, a landing gearsystem, a thrust reverser control system, a wing elements controlsystem, etc.

Although the electromechanical actuator disclosed here has a specificarchitecture, the latter may of course be different. The invention mayfor instance be applied to an actuating system comprising anelectromechanical actuator having two different redundant channels, witheach channel having its own communication module, its own power module,and if need be its own engine and its own actuating member. Each channelis also associated with different configuration data, in order toimplement different servo-control algorithms.

The digital transmission channel disclosed here is relatively complex,because of the array arrangement of the electromechanical actuators. Theinvention can of course be applied to an actuating system comprising adifferent digital transmission channel, such as a simple digital bus.

What is claimed is:
 1. An actuating system for an aircraft comprising:an electromechanical actuator (25) comprising: an electric motor (55), apower module (54) operative to generate a current supplied to theelectric motor, measuring means (59) adapted for measuring aservo-control magnitude of the electromechanical actuator and forgenerating a digital measurement signal representative of theservo-control magnitude, and a non-volatile memory (60), said memorybeing operative to store data (61) including configuration data (62)specific to the electromechanical actuator; a control unit (22)connected to the electromechanical actuator and operative to execute aservo-control algorithm by acquiring and using said configuration datato adapt the servo-control algorithm to the electromechanical actuator,wherein the servo-control algorithm implements a servo-control loophaving a feedback signal comprising the digital measurement signal andan output signal comprising a digital signal (55) for controlling theelectric motor of the electromechanical actuator and sent to the powermodule; at least one digital transmission channel (50) connecting thecontrol unit and the electromechanical actuator and enabling the routingbetween the control unit and the electromechanical actuator of thedigital measurement signal, the stored data and the digital controlsignal.
 2. The system according to claim 1, wherein the configurationdata comprises parameters (63) of the servo-control algorithm.
 3. Thesystem according to claim 2, wherein the parameters (63) comprise atleast one of: a proportional coefficient, an integral coefficient, aderived coefficient of the servo-control loop, a position limitation, aspeed limitation, and a power limitation of the electromechanicalactuator.
 4. The system according to claim 1, wherein the configurationdata (62) comprises parameters (63) of another algorithm.
 5. The systemaccording to claim 4, wherein the other algorithm comprises at least oneof: a failure detection algorithm, a trend following algorithm, and acycle counting algorithm.
 6. The system according to claim 1, whereinthe configuration data (62) comprises an identifier (80) enabling thecontrol unit to select the servo-control algorithm to be used among alist of servo-control algorithms stored in the control unit.
 7. Thesystem according to claim 1, wherein the configuration data comprises anative code of the servo-control algorithm.
 8. The system according toclaim 1, wherein the configuration data comprises electromechanicalactuator calibration data.
 9. The system according to claim 8, whereinthe calibration data comprises a native code of a calibration algorithm.10. The system according to claim 9, wherein the calibration algorithmis at least one of: a gradient correction, an offset correction, and acorrection according to a parameter measured in the electromechanicalactuator.
 11. The system according to claim 1, wherein the stored datafurther comprises data transmitted by the control unit.
 12. The systemaccording to claim 11, wherein the data transmitted by the control unitcomprises information on the utilization of the electromechanicalactuator.
 13. The system according to claim 1, wherein the stored datais protected by a checking tool of the cyclic redundancy check type. 14.The system according to claim 1, wherein the electromechanical actuatorcomprises two redundant channels which different configuration data isassociated with, in order to implement different servo-controlalgorithms.
 15. The system according to claim 1, wherein the at leastone digital transmission channel comprises two digital transmissionchannels connect the control unit and the electromechanical actuator.16. The system according to claim 15, wherein the two digitaltransmission channels comprise a fast channel for exchanging the digitalmeasurement signal and the digital control signal, and a slow channelfor transmitting the stored data.
 17. The system according to claim 1,wherein some of the stored data is read-accessible and/orwrite-accessible by a wireless interrogation device using RIFD-typetechnology.